1. Field of the Invention
The present invention generally relates to cooling apparatus using boiling and cooling refrigerant. More particularly the present invention relates to a cooling apparatus effectively used for cooling a heating element, such as power element like IGBT(Insulated-Gate Bipolar Transistor), composing a power control unit, such as general-purpose inverter, which cools and liquefies a refrigerant gasified by a heat from the heating element.
2. Description of the Related Art
In a general-purpose inverter for variably controlling the rotational speed of an industrial motor, for example, a power element, such as IGBT, which is a main device composing the circuit of the inverter, is used. As such power element in operation generates a large quantity of heat, a cooling unit is provided in accompaniment to the power element.
Specifically, a power pack accommodating a heating element such as power element therein is mounted on radiation fins composed of materials having a high heat conductivity, such as aluminum, to release the heat generated by the power element. More specifically, the power pack is closely fixed to the radiation fins made of aluminum by bolts or the like, and air flow generated by the radiation fins is flowed to the radiation fins. This forced air cooling apparatus has been employed in many cases. However, when such forced air cooling apparatus is employed, a cooling fan is continuously driven, and this increases the operation cost and the durability, etc. of the motor of the cooling fan become concerns. In order to solve these problems, it is conceivable to remove the cooling fan. However, without the cooling fan, the heat radiation ability would degrade and alternatively it would be required to enlarge the physical frame of the radiation fins.